Apparatus for resharpening drill bits



Sept. 8, 1964 w. F. KEMPE APPARATUS FOR RESHARPENING DRILL BITS 2Sheets-Sheet 2 Filed Dec. 3, 1962 INVENTOR 714547-52 F: HEMPE ATTORNE Y.

United States Patent 3,147,572 APPARATUS FOR RESHARPENING DRILL BITSWalter F. Kempe, Salt Lake City, Utah, assignor to Christensen DiamondProducts Company, Salt Lake City, Utah, a corporation of Utah Filed Dec.3, 1962, Ser. No. 241,816 18 Claims. (Cl. 51-15) The present inventionrelates to apparatus for sharpening bits, and more particularly toapparatus for sharpening bits having diamond cutting elements.

Diamond drill bits used in mining, oil well drilling, coring, concretecutting, and similar operations, become dull as'a result of loss ofdiamond elements from the exposed faces of the matrices in which theyare embedded. Diamond drill bits of the impregnated type have diamondcutting elements dispersed throughout the supporting matrix. As aresult, a dull bit may be resharpened by removing some of the matrixmaterial from the bit crown to expose additional diamonds. Suchresharpening can be repeated whenever necessary so long as sufficientdiamond elements are still present in the remaining matrix.

An object of the present invention is to provide an apparatus forsharpening diamond drill bits, and the like, by blasting abrasiveparticles against their cutting faces in such manner as to exposeprimarily the leading portions of the diamond cutting elements of thebit, without subs'tantially exposing their trailing portions, therebyeffectively supporting the rear or trailing portions of the diamondelements by matrix material, and enhancing their useful life.

' Another object of the invention is to provide apparatus for sharpeninga diamond drill bit, and the like, in which abrasive material is blastedagainst the bit in such manner as to rotate the bit in order that itsentire circumference is subject to the abrasive stream.

A further object of the invention is to provide an apparatus forsharpening diamond drill bits, and the like, by blasting abrasivematerial against their cutting faces, the apparatus being readilyadjusted to support drill bits of different sizes inappropriatedilferent positions, so. that the abrasive stream can actupon their working faces and expose the cutting elements embeddedtherein.

An additional object of the invention is to provide an apparatus forsharpening diamond drill bits, and the like, in which a stream ofabrasive material is blasted against the bit to rotate it and alsoefiect its sharpening, and in which rotation of the bit may be retardedto prevent its overspeeding by the abrasive stream. If desired, rotationof the bit by the abrasive stream may be assisted in lieu of beingretarded, as, for example, when the abrasive stream is rotating the bitat too slow a speed.

Yetanother object of the invention is to provide an apparatus forsharpening a diamond drill bit, and the like, by discharging a fluidstream from a nozzle or orifice through a mass of abrasive material todrive the latter against the bit, in which plugging of the nozzle ororifice by the abrasive material is prevented.

Still a further object of the invention is to provide an apparatus forblasting or jetting abrasive particles upon the drill bit, which canaccommodate drill bits of various sizes, and which is comparativelysimple, economical to manufacture, and of strong and sturdyconstruction.

This invention possesses many other advantages, and has other objectswhich may be made more clearly apparent from a consideration of a formin which it may be embodied. This form is shown in the drawingsaccompanying and forming part of the present specification. It will nowbe described in detail, for the purpose of illustrating the generalprinciples of the invention; but it is to be understood that suchdetailed description Ice a the invention is best defined by the appendedclaims.

Referring to the drawings:

FIGURE 1 is a Vertical section through an apparatus embodying theinvention;

FIG. 2 is a top plan view of the apparatus shown in FIG. 1;

FIG. 3 is a section taken along the line 3-3 on FIG. 2;

FIG. 4 is a cross-section taken along the line 4-4 on FIG. 1;

FIG. 5 is an enlarged fragmentary section taken along the line 55 onFIG. 1;

FIG. 6 is an enlarged vertical section taken along the line 66 on FIG.1;

FIG. 7 is a cross-section taken along the line 7-7 on FIG. 6.

The apparatus illustrated in the drawings is adapted to sharpen a drillbit A, such as a diamond drill bit, disclosed in FIG. 1 as being mountedin the apparatus. Specifically, the bit illustrated is designed to cut acore, and includes a generally annular body 10 having an upper threadedpin 11 for connection to a tubular drill string (not shown), which isused in rotating the core bit. The lower portion 12 of the bit body maycomprise a suitable matrix throughout which diamond particles or stones13 are dispersed, the diamonds projecting from the bit crown, as fromits lower face 14, inner face 15, and outer reaming face 16.

The diamonds or corresponding cutting elements 13 embedded in the matrixnormally project from the matrix to some extent for operation upon thematerial in which the cutting action is being performed. The diamondelements may break off or otherwise become lost during the drillingoperation, which severely reduces the drilling effectiveness of thedrill bit. By virtue of the apparatus illustrated in the drawings, aportion of the matrix material may be eroded away by blasting abrasiveparticles against the cutting faces 14, 15, 16 of the bit, resulting inexposure of additional diamond elements in the matrix, whereupon the bitA can again be used for the purpose of drilling the hole in theparticular material to which it is applied. The resharpening of a drillbit can take place repeatedly, so long as there are sufiicient diamondelements 13 embedded in its matrix.

As shown in the drawings, the apparatus includes an outer casing orhousing 17 supported above a suitable surface S, such as the ground orfloor, by supporting legs 18, the upper ends of which are receivedwithin housing sockets 19. The drill bit A can be appropriatelysupported Within an adapter 20 capable of accommodating bits havingthreaded pins 11, as illustrated, or threaded boxes (not shown). Oneside of the adapter 20 has a rubber or rubber-like ring 21 securedtherewithin into which the threaded pin 11 of the bit can be forced. Theopposite side of the adapter has a rubber or rubber-like ring 22 mountedon its periphery so that a threaded box of a drill bit (not shown) maybe forced thereon.

The adapter 20 is mounted upon a vertical, rotatable shaft 23, either inthe position illustrated in FIG. 1, when a bit with a threaded pin 11 isto be resharpened, or such adapter is inverted from the position shownand is mounted on the shaft with the external rubber ring 22 facing in adownward direction. The hub 24 of the adapter may have teeth 25 thereonadapted to be embedded in the periphery of the rotatable shaft 23, theadapter being releasably attached to the shaft by a screw 26, or thelike, extending radially of the adapter and bearing against the shaft.The adapter 20 may be suitably placed on the shaft 23, preferably withthe lower face 14 of the bit crown in substantially the same horizontalplane as the lower end of the shaft. The adapter 20 hascircumferentially spaced longitudinal holes 27 therein for the passageof fluent material, and it may also Patented Sept. 8, 1964 havecircumferentially spaced longitudinal passages 28 in its inner hubportion to permit passage of fluent material therethrough.

/ The shaft 23 is disposed vertically in the casing or housing 17, beingsupported from a lid or supporting cover 30 of the housing by suitablethrust bearings. As shown, a nut 31 is threaded on the upper end of theshaft 23 externally of the cover, the nut bearing against the outer race32 of a ball thrust bearing 33, its lower race 34 engaging a spacersleeve 35 which contacts the inner race 36 of a lower ball thrustbearing 37, the lower race 38 of which rests upon an inwardly directedcover flange 39 surrounding an opening 40 through the cover 36 receivingthe shaft 23 and bearing structure 32. to 38. The shaft has an upwardlyfacing shoulder 41 bearing against the lower race 38 to resist upwardmovement of the shaft in the housing 17 A jetting or nozzle blastingdevice 42 includes a housing extension 43 which depends below the sumpor hopper portion 44 of the housing 17, the latter being adapted tocontain a suitable abrasive material, such as a grinding compound,si.icon carbide, or aluminum oxide, which, for example, may be of 36 to60 mesh. The nozzle structure 42 is adapted to blast a fluid stream,such as a stream of water, upwardly through the mass of abrasivematerial to drive the latter against the exposed faces 14, 15, 16 of thebit, thevertical central portion of the crown of which preferably isaligned with the plane in which the fluid stream discharges from thenozzle structure.

The nozzle structure 42 includes the housing extension, previouslyreferred to, to which a fluid or water inlet pipe 45 is connected, thewater flowing through a housing inlet 46 into a chamber 47 in thehousing extension. The lower end of the chamber is closed by a pliant,elastic diaphragm 48 clamped against the lower end of the housingextension by a lower cover 49 secured to the housing flange 58 by bolts51. Assurance is had against leakage of fluid from the chamber 47 byproviding a suitable sealing gasket 52, such as a rubber or rubberlikeO-ring, in a groove 53 in the cover which engages the underside of theflexible diaphragm 48. diaphragm surrounds the lower stem 54 of avertically disposed valve member or head 55.

The lower end of the stem 54 is constituted as a flange 56 engaging aspring seat 57 surrounding the stem to hold the seat against the centralportion of the diaphragm 48 and press such central portion against thelower end of the valve head 55. A helical compression spring 58 isdisposed in a socket 59 in the lower cover as, bearing against the baseof the socket and against the spring seat 57 so as to urge the head 55in an upward direction and across the inlet end 66 of an inclinedorifice 61 formed in a nozzle 62 made of suitable material. Upwardmovement of the nozzle 62 is limited by engagement of its externalflange 63 with a gasket or seal 64 surrounding the nozzle structure, theseal being forced against the opposed horizontal face 65 of the housingextension. The upper end 66 of the valve member or head is pilotedwithin a nozzle socket 67, the inclined orifice 61 extending through theupper or base portion 68 of the socket, the periphery of the valvemember or head being in spaced relation to the inner wall of the socketto form an annular passage 69 through which fluid can pass.

When the spring 58 moves the valve member 55 upwardly to engage itsupper end 66 with the base 68 of the nozzle and across the inclinedorifice 61, the latter is closed against the passage of fluidtherethrough either in an upward or a downward direction. To insureagainst leakage of fluid between the valve member 55 and the base 68 ofthe nozzle, a suitable seal ring 78, such as a rubber or rubber-likeO-ring, is disposed in a circumferential a ute angle groove 71 formed inthe upper edge portion of the valve member. Such seal ring 70 willengage the base 68 of the nozzle when the valve head 55 is urgedupwardly thereagainst by the spring 58, to insure The flexible againstleakage of fluid around the head 55 and through the inclined orifice 61,or to insure against reverse flow of fluid downwardly through theorifice 61 and around the head 55.

To prevent foreign particles from passing upwardly into the orifice 61,which might effect its plugging, fluid entering the housing chamber 47passes through a cylindrical screen or filter member 72, the lower endof which bears against the diaphragm 48 and the upper end of which bearsagainst the nozzle flange 63, in order to hold the nozzle 62 in itsupward position and compress the gasket seal 64 between the flange 63and the housing 17.

The supporting cover 30 of the housing has a downwardly facing generallyV-shaped circumferential groove 73 therein adapted to receive acompanion-shaped housing rim 74. The axis 75 of rotation of the shaft 23is eccentric to the center line 76 of the housing 17 and its cover 30 sothat turning of the cover 30 on the housing will shift the shaft axisrelative to the nozzle orifice 61 to obtain proper positioning of thecrown portions of diamond drill bits mounted in the adapter with respectto the orifice. The larger the diameter of the drill bit A to besharpened, the further away will the shaft 23 be disposed horizontallyfrom the nozzle. The nozzle stream will be directed midway of the radialface 14 of the bit crown, diverging outwardly and inwardly of the bitthereof so that the abrasive particles blasted upwardly by the fluidstream emanating from the nozzle orifice will cover all faces 14, 15, 16of the bit crown and effect their sharpening by exposing additionaldiamond elements. Appropriate indicia 77, 78 are provided forfacilitating adjustment of the supporting cover 30 on the housing 18.Thus, a fluid outlet boss 79 extending from the upper portion of thehousing adjacent to the cover may have a suitable indicating arrow 78thereon and the upper outer margin of the cover 30 may have suitableindicia 77 thereon corresponding to bit sizes. By turning the cover 30on the housing 17 until the size of the bit A in the housing, indicatedby the cover indicia 77, is opposite the companion arrow 78, the bitcrown is placed in the appropriate central position relative to theblasting orifice or nozzle 61. The supporting cover 30 may then beclamped in this position of adjustment.

As shown, the cover 30 is releasably clamped to the housing 17 bydiametrically opposed clamp members 80, each clamp member having ahorizontal arm 81 engaging the upper outer surface of the cover, thisarm merging into a loop 82, which, in turn, merges into a shank or legportion 83 extending through a hole 84 in a boss 86 integral with orsecured to the housing 17, and extending outwardly thereof. A helicalcompression spring 87 encompasses the shank 83 with its upper endbearing against the underside of the boss 85 and its lower end engaginga washer 88 bearing against a nut 89 threaded on the lower portion ofthe shank or leg.

By grasping a loop 82 and exerting an upward force against the action ofthe spring 87, the arm 81 can be removed from the cover, after which theclamp member is turned and released, the arm then being disposed to oneside of the cover. Upon replacement of the cover 30 on the housing 17,or its shifting to its appropriate adjusted position thereon, the clampmembers may be pulled upwardly and turned to dispose their arms 81 overthe cover, whereupon the clamp members are released to allow the springs87 to shift and hold the arms downwardly against the cover 30 and clampit to the housing 17.

It is to be noted that the orifice 61 is disposed in a vertical planeand is inclined substantially, as, for example, at an angle of about 45degrees to the horizontal, so that the fluid stream issuing therefromwill pick up and blast the abrasive sharpening material in the sump 44at an angle against the bit crown. In effect, the orifice 61 functionsas a turbine nozzle to rotate the bit A in a lefthand direction.Accordingly, the fluid, such as water,

emanating from the nozzle 61 will notonly blast the abrasive particlesin the hopper portion 44 of the housing against the crown of the bit,but it will also rotate the bit A, adapter 20, and shaft 23, the jetstream acting over the entire circumference and over all working faceareas of the bit crown.

If the fluid stream directed against the bit crown rotates the bit A attoo great a speed, or at too slow a speed, the speed can be retarded orincreased by a hydraulic device mounted at the upper portion of theapparatus. As shown, an impeller or brake wheel 90 is mounted on theupper portion of the shaft 23, being secured thereto by a suitable screw91 extending through the hub 92 and bearing against the shaft. Theperipheral portion of the impeller has blades or teeth 93 against whicha horizontal fluid stream from a nozzle or orifice 94 can be directed.Fluid, such as water, can enter the nozzle through a fluid inlet pipe95, the nozzle being carried by the cover 30. As shown, an upper flange96 of the nozzle engages the upper side of the cover 30. The nozzle canbe clamped in diflerent positions of adjustment by a clamp nut 97threaded on the nozzle and adapted to bear against the underside of thecover 30. By loosening the clamp nut 97, the nozzle can be turned in thecover to a position in which its horizontal orifice 94 can direct thejet of water against the teeth 93 to tend to rotate the rotor 90 in acounterclockwise direction, which is the same direction as the shaft 23and bit are being turned by the jet stream issuing from the blastingnozzle or orifice 61. When in that position, rotation of the diamonddrill bit A will be assisted. If, however, the clamp nut 97 is loosenedand the nozzle 94 turned so that its orifice faces in another directionto impinge against the teeth 93 and tend to rotate the turbine rotor 90in a clockwise direction, such action will serve as a hydraulic brake toresist rotation of the bit A by the jet stream issuing from the blastingorifice 61. The brake or drive nozzle 94 can be adjusted in the cover 30to occupy one position or another, and will then be locked in suchposition by tightening the lock nut 97 against the underside of thecover. The

driving or braking position of the nozzle can be indicated by a suitablepointer 98 formed on the nozzle which coacts with suitable indicia 99 onthe cover adjacent thereto (FIG. 2

Usually, for relatively small bits A, the jet stream issuing from theblasting nozzle 61 tends to rotate the bit at too high a speed, in whichevent the upper nozzle 94 will be adjusted to occupy a position todirect a stream in a countering direction against the rotor blades orteeth 93, thereby functioning of the hydraulic brake. If, however, alarge diameter bit is to be sharpened, the stream emanating from theblasting nozzle 61 may be incapable of turning it at a sufiicient speed,in which event the upper nozzle 94 will be adjusted to direct its streamagainst the turbine wheel or rotor 90 and assist the rotation of the bitin a counterclockwise direction.

In the use of the apparatus, the bit A is mounted in an adapter 20 of asuitable size, which is then slipped over the shaft 23 and placed inappropriate position thereon, the screw 26 being tightened to firmlyattach the adapter to the shaft. Surrounding the shaft 23, bit A, andadapter 20 is a baffle structure, including a cylindrical innerenclosure 100, its lower end resting upon a lower shoulder 101 at theupper end of the sump or hopper portion 44 of the housing 17. This innerenclosure has its upper end 102 terminating below the turbine wheel 90and has a plurality of longitudinally spaced annular deflectors 103welded or otherwise secured thereto which serve to minimize the tendencyof the abrasive material to rise in the housing with the fluid or waterstream. As the water or other fluid emanating from the blasting nozzle61 jets through the abrasive material to drive the latter against thebit A, the water and abrasive material will then pass laterally inwardlyand outwardly of the bit, the fluent mixture rising in the housing 17and within the inner enclosure 100. The abrasive particles, beingheavier, will tend to drop out of the liquid back into the hopper 44 andsuch action is facilitated by the longitudinal passages 27, 28 throughthe bit adapter 20 and between the hub 24 of the adapter and the shaft23. The liquid rises in the housing over the uppermost baflle plate 103,flowing toward a liquid outlet 105 that has a suitable pipe 106connected thereto, the outlet being provided in the boss 7 9 carryingthe indicating arrow 78.

An outer cylindrical enclosure 107 surrounds the inner enclosure 100 inspaced relation thereto, its lower end resting upon supporting lugs 108projecting inwardly from the wall of the outer casing or housing 17.Abrasive particles that may still remain in the liquid when it passesover the uppermost transverse baffle member 103 can drop downwardly intothe annular space 109 between the inner and outer enclosures 100, 107.Liquid passing around the upper end 110 of the outer enclosure, whichextends upwardly above the upper baflie member 103, can still dropabrasive particles down into the annular space 111 between the outerenclosure 107 and the inner wall of the housing 17. If the lower part ofthe housing 17 between the inner enclosure 100 and the housing wallcontains a substantial amount of abrasive material, such material canreadily be shifted back into the sump or hopper portion 44 of thehousing by elevating the enclosures 100, 107 from the shoulder 101 andsupporting lugs 108.

In sharpening the bit A, it is mounted in the adapter 20 and the lattermounted on the shaft 23 in the manner described above. The upper nozzle94 is adjusted to its braking or drive position, depending upon the sizeof the bit mounted in the adapter. The cover 30, with the nozzle 94,turbine wheel 90, shaft 23, adapter 20, and bit A carried thereby isthen disposed above the housing and the bit, adapter and shaft inserteddown through the bafiies 103 until the cover engages the rim 74. Thecover 30 is then turned to align the bit size identification 77 with theboss indicator 78, whereupon the clamp loops 82 are pulled upwardly andturned to place their arms 81 against the cover to hold the latteragainst the housing rim (FIG. 5). Fluid, such as water, from a suitablesource and at a proper pressure is then allowed to enter the fluid inletpipes 45, 95. The fluid under pressure flows into the chamber 47 andpasses through the screen 72, acting upon the diaphragm 48 and urgingits central portion downwardly to shift the valve head 55 from itsengaging seat provided by the base 68 of the blasting nozzle 62, thewater then passing around the upper peripheral portion of the valve head55 and into the inclined orifice 61. The water emanates at high velocityfrom the nozzle orifice 61, blasting through the abrasive particles inthe hopper portion 44 and driving them in an inclined direction againstthe crown of the bit A, rotating the bit in a counterclockwise directionand causing the stream of jetted particles to cover the entirecircumference and all surfaces 14, 15, 16 of the bit crown. Dependingupon the adjustment of the upper nozzle 94, the water or other liquidissuing from its orifice 98 will act upon the rotor 90 and either assistor retard the action of the lower nozzle stream in rotating the bit,resulting in turning of the bit at the desired speed.

It is to be noted that the nozzle 61 jets the abrasive particles againstthe bit matrix in advance of each diamond element 13, and will erodeaway the matrix material in advance of the diamond element as regardsclockwise turning of the bit when drilling a hole. A much lesser erosionwill occur at the trailing sides of the diamond elements 13, matrixmaterial remaining to support such trailing side and thereby minimizingbreakage, or other fracture, and loss of diamond elements from the bit.As noted above, the inclination of the orifice 61 not only effects thesharpening of the bit by exposing the leading portions of the diamondelements 13, but also provides the motivating fluid for rotating the bitabout the shaft axis 75. As stated above, the stream issuing from thenozzle 61 will blast the abrasive particles over the entire face orcrown of the bit, and effectively sharpen the latter by exposing thediamond cutting elements 13.

After the bit has been sharpened, the supply of Water or other liquid tothe nozzles 62, 94 is shut off. As soon as the pressure of the waterdecreases to a sufiicient degree, the spring 58 will shift the head 55upwardly against its companion seat or nozzle base 68 to close theorifice 61. Such closing of the orifice 61 prevents liquid from flowingback through it and prevents abrasive particles from being carried backinto the orifice and possibly plug it or restrict subsequent flow ofliquid therethrough. Thus, the orifice 61 is automatically closed whenliquid is not passing through it and is automatically opened when liquidunder pressure is again allowed to flow through the inlet pipe 45 intothe housing chamber 47.

In the event that a different size bit is to be sharpened, it is mountedin the adapter 20, which is again appropriately fixed to the shaft 23and the apparatus reinserted in the housing 17, the cover 39 beingturned so that the bit and shaft axis 75 are again shifted relative tothe blasting nozzle orifice 61 to properly locate the bit crown withrespect thereto, the operator being able to use the convenient indicia77 on the housing cover 30 for this purpose. The clamps 80 are thenshifted over the housing cover 30 to hold it in place and the liquidagain allowed to pass into the upper and lower nozzles 94, 62, the uppernozzle 94 having first been appropriately positioned to function as aturbine drive device or as a hydraulic brake with respect to the turbinerotor 90.

I claim:

1. In abrasive blasting apparatus for drill bits: means for mounting thedrill bit for rotation about an axis; means adapted to contain aquantity of abrasive material; said mounting means supporting the drillbit adjacent to the quantity of abrasive material in said containingmeans; nozzle means having an axis inclined to the face of said bit andpositioned to direct a fluid into and through the abrasive material toblast said material in said containing means directly against the drillbit; the direction of discharge from said nozzle means beingsubstantially inclined to the face of said bit, whereby the fluid andabrasive material striking the bit rotate the bit about said axis ofrotation.

2. In abrasive blasting apparatus for drill bits: means for mounting thedrill bit for rotation about an axis; means adapted to contain aquantity of abrasive material; said mounting means supporting the drillbit adjacent to the quantity of abrasive material in said containingmeans; nozzle means having an axis inclined to the face of said list andpositioned to direct a fluid into and through the abrasive material toblast said material in said containing means directly against the drillbit; the direction of discharge from said nozzle means being inclinedsubstantially to the face of said bit in such direction that the fluidand abrasive material striking the bit rotate the bit counterclockwiseabout said axis of rotation.

3. In abrasive blasting apparatus for drill bits: means for mounting thedrill bit for rotation about an axis; means adapted to contain aquantity of abrasive material; said mounting means supporting the drillbit adjacent to the quantity of abrasive material in said containingmeans; nozzle means having an axis inclined to the face of said bit andpositioned to direct a fluid into and through the abrasive material toblast said material in said containing means directly against the drillbit; the direction of discharge from said nozzle means being inclinedsubstantially to the face of said bit, whereby the fluid and abrasivematerial striking the bit rotate the bit about said axis of rotation;and means for varying the position of said mounting means to shift saidrotational axis with respect to said nozzle means and the direction ofdischarge of fluid therefrom.

4. In abrasive blasting apparatus for drill bits: means for mounting thedrill bit for rotation about an axis;

means comprising a nozzle for blasting abrasive material against thedrilling face of the drill bit; said nozzle having an axis inclined tothe face of the bit, the direction of discharge from said nozzle beinginclined substantially to the drilling face of the bit, whereby theabrasive material striking the drilling face rotates the bit about saidaxis of rotation.

5. In abrasive blasting apparatus for drill bits: means for mounting thedrill bit for rotation about an axis; means comprising a nozzle forblasting abrasive material against the drilling face of the drill bit;said nozzle having an axis inclined to the face of the bit; thedirection of discharge frorn said nozzle being inclined substantially tothe drilling face of the bit in such direction that the abrasivematerial striking the drilling face rotates the bit counterclockwiseabout said axis of rotation.

6. In abrasive blasting apparatus for drill bits: means for mounting thedrill bit forrotation about an axis; means comprising a nozzle forblasting abrasive material against the drilling face of the drill bit;said nozzle having an axis inclined to the face of the bit; thedirection of discharge from said nozzle being inclined substantially tothe drilling face of the bit, whereby the abrasive material striking thedrilling face rotates the bit about said axis of rotation; and means forvarying the position of said supporting means to shift said rotationalaxis with respect to said nozzle and the direction of dischargetherefrom.

7, In abrasive blasting apparatus for drill bits: means for mounting thedrill bit for rotation about an axis; means adapted to contain aquantity of abrasive material; said mounting means supporting the drillbit adjacent to the quantity of abrasive material in said containingmeans; nozzle means having an axis inclined to the face of said bit andpositioned to direct a fluid into and through the abrasive material toblast said material in said containing means directly against the drillbit; the direction of discharge from said nozzle means being inclinedsubstantially to the face of said bit, whereby the fluid and abrasivematerial striking the bit rotate the bit about said axis of rotation;and brake means operatively connected to said mounting means forretarding rotation of the bit by the fluid and abrasive materialstriking thereagainst.

8. In abrasive blasting apparatus for drill bits: means for mounting thedrill bit for rotation about an axis; means adapted to contain aquantity of abrasive material; said mounting means supporting the drillbit adjacent to the quantity of abrasive material in said containingmeans; nozzle means having an axis inclined to the face of said bit andpositioned to direct a fluid into and through the abrasive material toblast said material in said containing means directly against the drillbit; the direction of discharge from said nozzle means being inclinedsubstantially to the face of said bit, whereby the fluid and abrasivematerial striking the bit rotate the bit about said axis of rotation;and means operatively connected to said mounting means and selectivelyshiftable to retard rotation of the bit by the fluid and abrasivematerial striking thereagainst or to assist such rotation of the bit.

9. In abrasive blasting apparatus for drill bits: means for mounting thedrill bit for rotation about an axis; means comprising a nozzle forblasting abrasive material against the drilling face of the drill bit;said nozzle having an axis inclined to the face of the bit; thedirection of discharge from said nozzle being inclined substantially tothe drilling face of the bit, whereby the abrasive material striking thedrilling face rotates the bit about said axis of rotation; and brakemeans operatively connected to said mounting means for retardingrotation of the bit by the material striking thereagainst.

10. In abrasive blasting apparatus for drill bits: means for mountingthe drill bit for rotation about an axis; means comprising a nozzle forblasting abrasive material against the drilling face of the drill bit;said nozzle having an axis inclined to the face of the bit; thedirection of discharge from said nozzle being inclined substantially tothe drilling face of the bit, whereby theabrasive material striking thedrilling face rotates the bit about said axis of rotation; and meansoperatively connected to said mounting means and selectively shiftableto retard rotation of the bit by the material striking thereagainst orto assist such rotation of the bit.

11. In abrasive blasting apparatus for drill bits: a housing adapted tocontain a quantity of abrasive material; a cover closing the upperportion of said housing and turnable on said housing about its axis; ashaft rotatably carried by said cover eccentrically of and substantiallyparallel to the housing axis; means secured to said shaft for supportinga drill bit in said housing; nozzle means mounted in said housing andpositioned to direct a fluid into and through the abrasive material toblast said material in said housing directly against the drill bit; saidcover being turnable on said housing and about its axis to adjust theposition of said shaft and drill bit carried thereby laterally withrespect to said nozzle means and the direction of fluid dischargedtherefrom.

12. In abrasive blasting apparatus for drill bits: a housing adapted tocontain a quantity of abrasive material; a cover closing the upperportion of said housing and turnable on said housing about its axis; ashaft rotatably carried by said cover eccentrically of and substantiallyparallel to the housing axis; means secured to said shaft for supportinga drill bit in said housing; nozzle means mounted in said housing andpositioned to direct a fluid into and through the abrasive material toblast said material in said housing directly against the drill bit; saidcover being turnable on said housing and about its axis to adjust theposition of said shaft and drill bit carried thereby laterally withrespect to said nozzle means and the direction of fluid dischargedtherefrom; said nozzle means having an axis inclined to the face of thebit, the direction of discharge from said nozzle means being inclinedsubstantially to the face of the bit, whereby the fiuid and abrasivematerial striking the bit rotate the bit and its supporting means andshaft.

13. In abrasive blasting apparatus for drill bits: a housing adapted tocontain a quantity of abrasive material; a cover closing the upperportion of said housing and turnable on said housing about its axis; ashaft rotatably carried by said cover eccentrically of and substantiallyparallel to the housing axis; means secured to said shaft for supportinga drill bit in said housing; nozzle means mounted in said housing andpositioned to direct a fluid into and through the abrasive material toblast said material in said housing directly against the drill bit; saidcover being turnable on said housing and about its axis to adjust theposition of said shaft and drill bit carried thereby laterally withrespect to said nozzle means and the direction of fluid dischargedtherefrom; said nozzle means having an axis inclined to the face of thebit, the direction of discharge from said nozzle means being inclinedsubstantially to the face of the bit in such direction that the fluidand abrasive material striking the bit rotate the bit and its supportingmeans and shaft counterclockwise about the axis of said shaft.

14. In abrasive blasting apparatus for drill bits: a housing adapted tocontain a quantity of abrasive material; a cover closing the upperportion of said housing and turnable on said housing about its axis; ashaft rotatably carried by said cover eccentrically of and substantiallyparallel to the housing axis; means secured to said shaft for supportinga drill bit in said housing; nozzle means mounted in said housing andpositioned to direct a fluid into and through the abrasive material toblast said material in said housing directly against the drill bit; saidcover being turnable on said housing and about its axis to adjust theposition of said shaft and drill bit carried thereby laterally withrespect to said nozzle means and the direction of fluid dischargedtherefrom; said nozzle means having an axis inclined to the face of thebit, the direction of discharge from said nozzle means being inclinedsub- 10 stantially to the face of the bit,whereby the fluid and abrasivematerial striking the bit rotate the bit and its supporting means andshaft; and brake means operatively connected to said shaft for retardingrotation of the shaft by the fluid and abrasive material strikingthereagainst.

15. In abrasive blasting apparatus for drill hits: a housing adapted tocontain a quantity of abrasive material; a cover closing the upperportion of said housing and turnable on said housing about its axis; ashaft rotatably carried by said cover eccentrically of and substantiallyparallel to the housing axis; means secured to said shaft for supportinga drill bit in said housing; nozzle means mounted in said housing andpositioned to direct a fluid into and through the abrasive material toblast said material in said housing directly against the drill bit; saidcover being turnable on said housing and about its axis to adjust theposition of said shaft and drill bit carried thereby laterally withrespect to said nozzle means and the direction of fluid dischargedtherefrom; said nozzle means having an axis inclined to the face of thebit, the direction of discharge from said nozzle means being inclinedsubstantially to the face of the bit, whereby the fluid and abrasivematerial striking the bit rotate the bit and its supporting means andshaft; and means operatively connected to said shaft and including meanswhich is selectively shiftable to either retard rotation of the bit bythe fluid and abrasive material striking thereagainst or to assist suchrotation of the bit.

16. In abrasive blasting apparatus for drill hits: a housing adapted tocontain a quantity of abrasive material; a cover closing the upperportion of said housing and turnable on said housing about its axis; ashaft rotatably carried by said cover eccentrically of and substantiallyparallel to the housing axis; means secured to said shaft for supportinga drill bit in said housing; nozzle means mounted in said housing andpositioned to direct a fluid into and through the abrasive material toblast said material in said housing directly against the drill bit; saidcover being turnable on said housing and about its axis to adjust theposition of said shaft and drill bit carried thereby laterally withrespect to said nozzle means and the direction of fluid dischargedtherefrom; said nozzle means having an axis inclined to the face of thebit, the direction of discharge from said nozzle means being inclinedsubstantially to the face of the bit, whereby the fluid and abrasivematerial striking the bit rotate the bit and its supporting means andshaft; a rotor secured to said shaft; and a shiftable nozzle adapted tojet fluid against said rotor in one direction to resist rotation of saidshaft and bit or in another direction to assist rotation of said shaftand bit.

17. In abrasive blasting apparatus for drill hits: a housing adapted tocontain a quantity of abrasive material; a cover closing the upperportion of said housing and turnable on said housing about its axis; ashaft rotatably carried by said cover eccentrically of and substantiallyparallel to the housing axis; means secured to said shaft for supportinga drill bit in said housing; nozzle means mounted in said housing andpositioned to direct a fluid into and through the abrasive material toblast said material in said housing directly against the drill bit; saidcover being turnable on said housing and about its axis to adjust theposition of said shaft and drill bit carried thereby laterally withrespect to said nozzle means and the direction of fluid dischargedtherefrom; means releasably securing said cover to said housing toretain said shaft and drill bit in various positions of adjustmentrelative to said nozzle means; said nozzle means having an axis inclinedto the face of the bit, the direction of discharge from said nozzlemeans being inclined substantially to the face of the bit in suchdirection that the fluid and abrasive material striking the bit rotatethe bit and its supporting means and shaft counterclockwise about theaxis of said shaft; a rotor secured to said shaft; and a shiftablenozzle adapted to jet fluid against said rotor in a clockwise directionto resist counterclockwise rotation of said shaft and bit, or in acounterclockwise direction to assist counterclockwise rotation of saidshaft and bit. 1

18. In abrasive blasting apparatus for drill bits: means mounting thedrill bit for rotation about an axis; means comprising a nozzle forblasting abrasive material against the drilling face of the drill bit;said nozzle having an axis inclined to the face of the bit; thedirection of discharge from said nozzle being inclined substantially tothe drillirig face of the bit, whereby the abrasive material strikingthe drilling face rotates the bit about said axis of rotation; a rotorsecured to said mounting means; and a shiftable nozzle adapted to jetfluid against said rotor in one direction to resist rotation of saidmounting means and bit or in another direction to assist rotation ofsaid mounting means and bit.

References Cited in the file of this patent UNITED STATES PATENTS2,395,420 Myers Feb. 26, 1946 2,594,735 Crumley Apr. 29, 1952 2,692,458Lawrence Oct. 26, 1954 10 3,044,219 Cutler July 17, 1962 FOREIGN PATENTS505,152 France Apr. 29, 1920

4. IN ABRASIVE BLASTING APPARATUS FOR DRILL BITS: MEANS FOR MOUNTING THEDRILL BIT FOR ROTATION ABOUT AN AXIS; MEANS COMPRISING A NOZZLE FORBLASTING ABRASIVE MATERIAL AGAINST THE DRILLING FACE OF THE DRILL BIT;SAID NOZZLE HAVING AN AXIS INCLINED TO THE FACE OF THE BIT, THEDIRECTION OF DISCHARGE FROM SAID NOZZLE BEING INCLINED SUBSTANTIALLY TOTHE DRILLING FACE OF THE BIT, WHEREBY THE ABRASIVE MATERIAL STRIKING THEDRILLING FACE ROTATES THE BIT ABOUT SAID AXIS OF ROTATION.